diff --git a/locust/debug.py b/locust/debug.py
index 3341549baa..1d765f3aba 100644
--- a/locust/debug.py
+++ b/locust/debug.py
@@ -22,7 +22,7 @@ class PrintListener:
 
     def __init__(
         self,
-        env: locust.env.Environment,
+        env: Environment,
         include_length=False,
         include_time=False,
         include_context=False,
@@ -122,11 +122,15 @@ def run_single_user(
         locust.log.setup_logging(loglevel)
 
     if not _env:
-        _env = locust.env.Environment(events=locust.events)
+        options = argument_parser.parse_options()
+
         # in case your test goes looking for the file name of your locustfile
-        _env.parsed_options = argument_parser.parse_options()
         frame = inspect.stack()[1]
-        _env.parsed_options.locustfile = os.path.basename(frame[0].f_code.co_filename)
+        locustfile = os.path.basename(frame[0].f_code.co_filename)
+        options.locustfile = locustfile
+
+        _env = Environment(events=locust.events, locustfile=locustfile, host=options.host, parsed_options=options)
+
         # log requests to stdout
         PrintListener(
             _env,
@@ -142,6 +146,8 @@ def run_single_user(
     _env.user_classes = [user_class]
     _env._filter_tasks_by_tags()
     _env.events.test_start.fire(environment=_env)
+    if _env.host:
+        user_class.host = _env.host
 
     # create a single user
     user = user_class(_env)
diff --git a/locust/test/test_debugging.py b/locust/test/test_debugging.py
new file mode 100644
index 0000000000..3941df0a14
--- /dev/null
+++ b/locust/test/test_debugging.py
@@ -0,0 +1,37 @@
+import os
+from threading import Timer
+from unittest import mock
+
+from locust import debug, task
+from locust.test.testcases import LocustTestCase
+from locust.user.task import LOCUST_STATE_STOPPING
+from locust.user.users import HttpUser
+
+
+class DebugTestCase(LocustTestCase):
+    def setUp(self):
+        super().setUp()
+        debug._env = None
+
+
+class TestDebugging(DebugTestCase):
+    @mock.patch.dict(os.environ, {"LOCUST_HOST": "http://localhost"})
+    def test_run_single_user_pass_host_to_user_classes(self):
+        """
+        HttpUser should receive host from environment variable
+        """
+
+        class MyUser1(HttpUser):
+            @task
+            def my_task():
+                pass
+
+        def _stop_user():
+            user = getattr(debug._env, "single_user_instance", None)
+            if user:
+                user._state = LOCUST_STATE_STOPPING
+
+        t = Timer(1, _stop_user)
+        t.start()
+
+        debug.run_single_user(MyUser1)